1. Field of the Invention
This invention relates to terminal assemblies for connecting a power conductor in electrical power apparatus to an external conductor, and particularly to such terminal assemblies that can be selectively applied in the field to provide either a screw binding connection or a pressure plate connection to the external conductor.
2. Background Information
Many types of electrical apparatuses have molded housings with external recesses into which power conductors within the apparatus extend for connection to an external conductor. It is common for the power conductor to be a flat strap of a conductive material such as copper. A terminal connector secures the external conductor to the strap. A common terminal connector comprises a collar having a through hole sized to slide onto the flat strap and through which the external conductor extends along the power conductor. A screw threaded through a transverse bore in the collar clamps the conductor and external conductor together to effect an electrical and mechanical connection.
There are two types of external conductors that are connected to the flat power conductor of electric power apparatus using such a terminal collar, solid wire and stranded wire. Typically, the solid round wire is placed between the flat power conductor and the screw, which is then threaded down to clamp the wire against the flat power conductor. If the same arrangement is used with stranded wire, the screw separates the wires clamping only a few, and breaking some, to make a poor electrical and mechanical connection. To avoid these problems, a pressure plate connection is made for stranded wire instead of the direct contact by the terminal screw. Such a pressure plate connection can be accomplished by attaching a pressure plate to the end of the screw so that the stranded wire is pressed against the flat conductor by an extended contact surface, or the stranded wire is placed on the opposite side of the flat conductor so that tightening the screw draws the collar toward the flat conductor clamping the stranded wire between the power conductor and the collar.
With the presently available terminal assemblies, suppliers and users must maintain an inventory of both types of devices, which is inconvenient and costly. Hence, there is room for improvement.